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The Blackstone Group's blockbuster agreement to buy the nation's largest office landlord - whose trophy properties include WorldWide Plaza in Manhattan, the Civic Opera building in Chicago and Columbia Center, Seattle's tallest tower - demonstrates that the U.S. commercial market hasn't lost its zing. It also will further reduce a shrinking public real estate market for investors.

Analysts, though, said the deal may be more a reflection of the current hunger among capital-flush private-equity firms for leveraged buyouts in general than a barometer of the commercial real estate sector.

"It's probably not as much industry-specific as it is that people want to get in on LBOs," said Linda Varoli, vice president of research at Wall Street Access, an institutional brokerage firm. "Sam Zell built this company, so it's kind of surprising he would want to sell it. But when you get offered a really good price like that, you have a responsibility to shareholders."

Equity Office has stakes in four Florida buildings. It owns the SunTrust Center in Orlando and 1200 Corporate Place in Boca Raton. In October, it acquired a 50 percent holding in two Miami office buildings: Wachovia Financial Center and 1221 Brickell Ave.

Blackstone agreed to pay an 8.5 percent premium to the closing price of Equity Office last Friday, and is taking on close to $17-billion in debt. That gives the deal announced late Sunday night a total value of $36-billion, which it said will be the largest private-equity transaction ever.

It's the New York-based private-equity firm's third purchase this year of a real estate investment trust and its 10th in two years, including 2006 deals for Carr- America Realty Corp. and, with partner Brookfield Properties Corp., for Trizec Properties Inc.

Real estate investment trusts are public companies that own and operate real estate and don't pay corporate income taxes as long as they distribute almost all their income to shareholders as dividends. They are popular among well-off investors because of their tax benefits, with many of the dividends either nontaxable or qualifying for reduced taxes.

Shares of Chicago-based Equity Office rose $3.42, or 7.7 percent, to close at $48.14 on the New York Stock Exchange after reaching an all-time high of $48.52.

Equity Office owns 580 U.S. buildings totaling more than 108-million square feet in 16 states and the District of Columbia. It was founded in 1976 by Zell, 65, the Chicago investor who early in his career earned the nickname "Grave Dancer" for his talent for spotting undervalued properties.

Zell remains chairman of the company, which went public in 1997, but is not part of the buyout group.